Let mediastreamer2 try to bind the RTP socket for IPv6 and if it fails fallback to IPv4.

This is to enable to call starting in IPv4 to continue in IPv6 in case of network switch.

src/conference/session/media-session.cpp

@@ -1122,7 +1122,7 @@ void MediaSessionPrivate::discoverMtu (const Address &remoteAddr) {
 
 string MediaSessionPrivate::getBindIpForStream (int streamIndex) {
 	L_Q();
-	string bindIp = lp_config_get_string(linphone_core_get_config(q->getCore()->getCCore()), "rtp", "bind_address", (af == AF_INET6) ? "::0" : "0.0.0.0");
+	string bindIp = lp_config_get_string(linphone_core_get_config(q->getCore()->getCCore()), "rtp", "bind_address", "");
 	PortConfig *pc = &mediaPorts[streamIndex];
 	if (!pc->multicastIp.empty()){
 		if (direction == LinphoneCallOutgoing) {
@@ -2367,7 +2367,7 @@ void MediaSessionPrivate::initializeAudioStream () {
 		if (remoteDesc)
 			streamDesc = sal_media_description_find_best_stream(remoteDesc, SalAudio);
 
-		audioStream = audio_stream_new2(q->getCore()->getCCore()->factory, getBindIpForStream(mainAudioStreamIndex).c_str(),
+		audioStream = audio_stream_new2(q->getCore()->getCCore()->factory, L_STRING_TO_C(getBindIpForStream(mainAudioStreamIndex)),
 			(multicastRole ==  SalMulticastReceiver) ? streamDesc->rtp_port : mediaPorts[mainAudioStreamIndex].rtpPort,
 			(multicastRole ==  SalMulticastReceiver) ? 0 /* Disabled for now */ : mediaPorts[mainAudioStreamIndex].rtcpPort);
 		if (multicastRole == SalMulticastReceiver)
@@ -2473,7 +2473,7 @@ void MediaSessionPrivate::initializeTextStream () {
 		if (remoteDesc)
 			streamDesc = sal_media_description_find_best_stream(remoteDesc, SalText);
 
-		textStream = text_stream_new2(q->getCore()->getCCore()->factory, getBindIpForStream(mainTextStreamIndex).c_str(),
+		textStream = text_stream_new2(q->getCore()->getCCore()->factory, L_STRING_TO_C(getBindIpForStream(mainTextStreamIndex)),
 			(multicastRole ==  SalMulticastReceiver) ? streamDesc->rtp_port : mediaPorts[mainTextStreamIndex].rtpPort,
 			(multicastRole ==  SalMulticastReceiver) ? 0 /* Disabled for now */ : mediaPorts[mainTextStreamIndex].rtcpPort);
 		if (multicastRole == SalMulticastReceiver)
@@ -2517,7 +2517,7 @@ void MediaSessionPrivate::initializeVideoStream () {
 		if (remoteDesc)
 			streamDesc = sal_media_description_find_best_stream(remoteDesc, SalVideo);
 
-		videoStream = video_stream_new2(q->getCore()->getCCore()->factory, getBindIpForStream(mainVideoStreamIndex).c_str(),
+		videoStream = video_stream_new2(q->getCore()->getCCore()->factory, L_STRING_TO_C(getBindIpForStream(mainVideoStreamIndex)),
 			(multicastRole ==  SalMulticastReceiver) ? streamDesc->rtp_port : mediaPorts[mainVideoStreamIndex].rtpPort,
 			(multicastRole ==  SalMulticastReceiver) ?  0 /* Disabled for now */ : mediaPorts[mainVideoStreamIndex].rtcpPort);
 		if (multicastRole == SalMulticastReceiver)